The design is not mechanically stable; a slight imbalance makes the armature stick to one pole of the magnet. A fairly stiff restoring force is required to hold the armature in the 'balance' position. Although this reduces its efficiency, this design can still produce more sound from less power than any other[clarification needed]. Popularized in the 1920s as Baldwin Mica Diaphragm radio headphones, balanced armature transducers were refined during World War II for use in military sound powered telephones. Some of these achieved astonishing electro-acoustic conversion efficiencies, in the range of 20% to 40%, for narrow bandwidth voice signals.

Those who buy either of these headphones are in for a treat. Our reviewer didn’t hold back in their assessment of these cans’ ability to fully realize every detail of a recording, noting their “warm and rigid bass, a midrange that dips close to the ruddy colors of analog tape saturation (without sacrificing an ounce of detail), and a laser tight response up top that helps illuminate vivid clarity and granular instrumental texture across the board.”

The SoundSport Wireless are wireless sport earbuds that are very similar to the SoundSport Free. Instead of being true wireless earbuds, however, the two SoundSport Wireless earbuds are tethered together by cable. Aside from that, the two wireless earbuds have similar audio performance and use the same Bose Connect app. The SoundSport Wireless will last longer on a single charge (as opposed to the SoundSport Free which recharge every time they go back in their case).
Binaural recordings use a different microphone technique to encode direction directly as phase, with very little amplitude difference below 2 kHz, often using a dummy head. They can produce a surprisingly lifelike spatial impression through headphones. Commercial recordings almost always use stereo recording, rather than binaural, because loudspeaker listening is more common than headphone listening.
The Soundsport Free, released in the fall of 2017, are Bose’s first truly wireless earbuds. They utilize the same StayHear+ Sport tips as the company’s other in-ear headphones, making them naturally more sweat-resistant and more secure than AirPods. They work with the Bose Connect app, which is pretty basic but does have a “Find My Buds” feature that, when enabled, can help you find your earbuds should you misplace them.
Sensitivity is a measure of how effectively an earpiece converts an incoming electrical signal into an audible sound. It thus indicates how loud the headphones are for a given electrical drive level. It can be measured in decibels of sound pressure level per milliwatt (dB (SPL)/mW) or decibels of sound pressure level per volt (dB (SPL) / V).[12] Unfortunately, both definitions are widely used, often interchangeably. As the output voltage (but not power) of a headphone amplifier is essentially constant for most common headphones, dB/mW is often more useful if converted into dB/V using Ohm's law:

If you’ll mostly be using headphones at your desk, install a headphone hook so you can safely stow yours when you’re not using them. Headphones can be fairly fragile, so it’s important to take care of yours and avoid tossing them around. A headphone hook gives your favorite pair a place to hang and creates a fun conversation piece for your workstation.

Circumaural headphones (sometimes called full size headphones or over-ear headphones) have circular or ellipsoid earpads that encompass the ears. Because these headphones completely surround the ear, circumaural headphones can be designed to fully seal against the head to attenuate external noise. Because of their size, circumaural headphones can be heavy and there are some sets that weigh over 500 grams (1 lb). Ergonomic headband and earpad design is required to reduce discomfort resulting from weight. These are commonly used by drummers in recording.
In the professional audio sector, headphones are used in live situations by disc jockeys with a DJ mixer, and sound engineers for monitoring signal sources. In radio studios, DJs use a pair of headphones when talking to the microphone while the speakers are turned off to eliminate acoustic feedback while monitoring their own voice. In studio recordings, musicians and singers use headphones to play or sing along to a backing track or band. In military applications, audio signals of many varieties are monitored using headphones.
In the professional audio sector, headphones are used in live situations by disc jockeys with a DJ mixer, and sound engineers for monitoring signal sources. In radio studios, DJs use a pair of headphones when talking to the microphone while the speakers are turned off to eliminate acoustic feedback while monitoring their own voice. In studio recordings, musicians and singers use headphones to play or sing along to a backing track or band. In military applications, audio signals of many varieties are monitored using headphones.
Earbuds have small speakers that rest on the ear canal of the wearer. These are usually much less expensive than on-ear and over-ear headphones and reproduce the sound well. However, outside sounds, such as traffic or power tools, can get past the earbuds and interfere with your enjoyment. Earbuds also don't stay in place very well if the wearer is moving much, such as exercising. These also are lower fidelity than on-ear and over-ear headphones.